We recently updated our UC520 to software pack 8.0.2. IOS 15.0(1)XA2
Since the upgrade, the phones have a very distorted ring, followed by a fairly loud click.
Voice call quality is fine.
We had a similar problem on 8.0.0, except that voice calls were distorted as well.
Downgrading the IOS back to 12.4 fixed the problem.
Anyone else experiencing this?